It says: “Impacts from agriculture are expected to increase substantially due to population growth increasing consumption of animal products. Unlike fossil fuels, it is difficult to look for alternatives: people have to eat. A substantial reduction of impacts would only be possible with a substantial worldwide diet change, away from animal products.”

Professor Edgar Hertwich, the lead author of the report, said: “Animal products cause more damage than [producing] construction minerals such as sand or cement, plastics or metals. Biomass and crops for animals are as damaging as [burning] fossil fuels.”

The panel of experts ranked products, resources, economic activities and transport according to their environmental impacts. Agriculture was on a par with fossil fuel consumption because both rise rapidly with increased economic growth, they said.

Ernst von Weizsaecker, an environmental scientist who co-chaired the panel, said: “Rising affluence is triggering a shift in diets towards meat and dairy products – livestock now consumes much of the world’s crops and by inference a great deal of freshwater, fertilisers and pesticides.”

Both energy and agriculture need to be “decoupled” from economic growth because environmental impacts rise roughly 80% with a doubling of income, the report found.

Achim Steiner, the UN under-secretary general and executive director of the UNEP, said: “Decoupling growth from environmental degradation is the number one challenge facing governments in a world of rising numbers of people, rising incomes, rising consumption demands and the persistent challenge of poverty alleviation.”